Pain on the Inner Side of the Knee: Possible Causes

The inner side of the knee is the area where the medial collateral ligament, the medial meniscus, and the joint capsule run close together. Pain in this area narrows the range of likely causes, but the exact diagnosis is made by a doctor after an examination and diagnostic testing.

What is located on the inner side of the knee

The knee joint consists of bones, cartilage, ligaments, and fluid; muscles and tendons help it move. The meniscus is a cartilage pad that cushions load and stabilizes the joint. The inner (medial) meniscus is less mobile than the outer one and is connected to the medial collateral ligament, so they are often injured together. Anteriorly, the menisci are connected by the transverse ligament.

Pain on the inner side of the knee: main causes

The most common closed injury of the knee joint is a meniscal tear. It occurs during a sharp rotation of the lower leg in the joint with the foot fixed; less often, when squatting or jumping. The injury itself may be minor. Tears can be traumatic, when a healthy meniscus is overloaded, or degenerative, when ordinary load falls on an already altered meniscus. With a bucket-handle tear of the medial meniscus, the torn part displaces into the joint cavity, becomes entrapped between the articular surfaces, and causes locking: sudden sharp pain and restricted movement.

Another cause is ligament sprains and injuries after overstretching, overload, or twisting, including in sports. If there was no obvious trauma, the doctor considers osteoarthritis (pain and stiffness in both knees, slight swelling, more often in older people), bursitis (warmth and redness, worse when kneeling and bending), gout, or septic arthritis (a hot red knee, a sudden attack of very severe pain); in adolescents, Osgood-Schlatter disease with pain and swelling below the patella.

The knee hurts when pressed: signs of meniscal damage

The doctor assesses tenderness on pressing during the examination, but by itself it does not identify the cause. With meniscal damage, there may be pain during physical activity, a click when bending, increased joint volume, elevated temperature in the joint area, and difficulty going up and down stairs. Immediately after the injury, the pain is diffuse; only after 2–3 weeks, when the reactive phenomena subside, can one speak specifically of a meniscal tear.

Pain when bending the knee on the inner side

With meniscal damage, there may be a characteristic click when bending the joint and pain during physical activity. If the joint is locked, a certain movement becomes impossible: the displaced fragment gets in the way. A tear in the vascular zone near the capsule can cause blood accumulation in the joint cavity — hemarthrosis, swelling slightly above the patella.

How the doctor determines the cause of pain: examination and testing

First, a discussion of the mechanism of injury and an examination: how the joint moves, whether there is swelling, locking, or instability. X-rays are needed to rule out damage to bone structures; the menisci themselves are not visible on them because they are transparent to X-rays. Next, the following are used:

• contrast-enhanced radiography of the joint;
• magnetic resonance imaging;
• ultrasound examination of the joint;
• endoscopic arthroscopy.

The doctor may refer for a scan or to a specialist if the cause remains unclear.

When knee pain requires urgent examination

One should see a doctor if the pain does not improve over several weeks. An urgent examination is needed for very severe pain, inability to move the knee, severe swelling, locking of the joint, twisting, and a painful click; a painless click is considered normal.

Pain on the inner side of the knee by itself is not a reason to call an ambulance; 103/112 — for severe trauma, if the knee has changed shape and it is impossible to bear weight on the leg, and also for high fever with redness and heat around the knee (possible infection).

This material is for reference: it lists possible causes but does not replace a doctor's consultation — what exactly hurts is shown by examination and testing.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer